The theory of the continuity of the germ plasm proposed by A. Weismann in 1886. It opposed the idea that acquired characteristics could be inherited. Weismann distinguished the body of the organism (the soma) from the reproductive cells (the germ plasm) and stated that it was the germ cells alone that affected inheritance and not the soma. He suggested that the germ plasm was set aside during early development and was not affected by subsequent changes in the soma. Weismann also formulated a theory of inheritance based on the behaviour of chromosomes. His ideas led to a rejection of *Lamarckism
that has continued to the present time.